In sub-Saharan Africa (sSA), the vast majority of the millions of pregnant women who are tested and counseled for HIV every year test negative for HIV antibodies. Keeping these women uninfected is a critical component of the World Health Organization (WHO) global strategy fror prevention of mother-to-child HIV transmission (PMTCT). Evidence shows that these women are at continuous risk of HIV acquisition during pregnancy and breastfeeding with HIV incidence rates ranging between 2 and 17 infections per 100 person years. HIV acquisition during pregnancy or breastfeeding puts mothers and babies at high risk for vertical HIV transmission because of the peak viremia that follows incident HIV infection in the mother. WHO thus recommends that in generalized epidemic settings, pregnant women who test HIV negative on their first antenatal visit retest in late pregnancy in order to detect incident infections and take appropriate PMTCT measures. However, this recommendation falls short of addressing the risks of incident HIV infection during breastfeeding and the need for primary HIV prevention. This study will test the hypothesis that extended repeat HIV testing and enhanced counseling (HTEC) during late pregnancy and breastfeeding can increase and/or sustain risk reduction behaviors and prevent incident STI and HIV infections among HIV-uninfected pregnant women and that couple HTEC can further enhance this effect. We will conduct a stratified randomized trial involving 1,230 HIV-uninfected pregnant women presenting individually (n=410) or in couples (n=410 women and 410 partners) in an urban and a rural public hospital in Uganda. Individual women and couples will be randomized to receive either repeat HIV testing and standard counseling (HTSC) in late pregnancy as per the WHO recommendation or repeat HIV testing and enhanced counseling (HTEC) during late pregnancy and breastfeeding (at 3, 6 12, 18 and 24 months or 6 weeks after the end of breastfeeding). Enhanced counseling will emphasize the concept of an HIV-free and healthy baby and family based on primary prevention, adequate infant feeding and family planning. Our specific aims will be: 1) to assess the effect of extended repeat HTEC on sexual risk behavior and the incidence of sexually transmitted infections (STIs) and HIV in uninfected pregnant and lactating women presenting individually;2) to assess the effect of extended repeat couple HTEC on sexual risk behavior and the incidence of STIs and HIV in uninfected pregnant and lactating women presenting with their partner, and 3) to assess the costs and estimate the cost-effectiveness of the intervention. We will compare the frequency of unprotected sex, and incidences of STI, HIV and recurrent pregnancies in intervention and comparison arms. Analyses will focus on the effect of individual and dyadic factors (couple communication and support) on risk behaviors and STI/HIV incidence. The findings of this study will inform policy about the effectiveness of retesting and counseling HIV-negative pregnant and lactating women in sSA. PUBLIC HEALTH RELEVANCE: As a result of scaling up PMTCT programs in sub-Saharan Africa, millions of pregnant women are tested and counseled for HIV every year in antenatal clinics. The great majority of these women test negative for HIV antibodies. Keeping these women uninfected through pregnancy and breastfeeding which can last up to 2 years is a critical component of the global strategy to eliminate pediatric HIV in sub-Saharan Africa. Pregnancy and the post-partum period are associated with biological as well as socio-cultural vulnerability to HIV. Maternal acquisition of HIV during pregnancy or breastfeeding is associated with a high risk of transmission to the infant as compared to established infection because of the peak viremia that follows acute or incident HIV infection in the mother. The WHO recommends that pregnant women who test HIV-negative at their first ANC visit get retested in late pregnancy or at delivery in generalized epidemic settings. However, this recommendation has been rarely implemented and there are no recommendations or evidence-based strategies addressing the risk of maternal HIV acquisition during the post-partum and breastfeeding periods. This study will assess an intervention to retest for HIV and provide enhanced counseling to HIV-negative pregnant women during pregnancy and throughout breastfeeding with an emphasis on reinforced risk reduction centered around the concept of an HIV-free family (or HIV-contained in case of serodiscordant couples). We will test this intervention in a randomized trial of pregnant women who present individually and those who present as couples for antenatal care in one urban and one rural hospital in Uganda. The findings of this study will provide evidence on the effectiveness and cost-effectiveness of the intervention and will inform national and regional policy on primary prevention of HIV in pregnant and lactating women, toward the ultimate goal of eliminating mother to child transmission of HIV.